1. Field of the Invention
The present invention relates to a gravity casting mold, which is provided with a heating sleeve in a first riser.
2. Description of the Related Art
Generally, gravity casting is a casting technology in which a molten metal poured into a casting mold is solidified by gravity of the molten metal. Gravity casting is characterized in that the molten metal quickly cools and can form fine crystal grains.
Particularly, gravity casting is preferably used by automobile manufacturers to cast a variety of parts for automobiles, such as engines composed of cylinder heads and cylinder blocks, camshafts, crankshafts, suction and exhaust manifolds, turbine housings, etc. To produce a part of an automobile, a body of the part is formed by gravity casting and is subjected to a variety of machining processes, so a cast product can be produced.
In recent years, the shape of an exhaust system of engines has been optimally designed according to wide use of a gasoline turbocharger, and this has led to active study of a technology of integrally producing a twin scroll turbocharger and an exhaust manifold in an effort to realize an improvement in durability and air-tightness of the parts and to realize an increase in a profit. That is, it is required to integrally cast a turbine housing for a twin scroll turbocharger and an exhaust manifold composed of four exhaust runners, in which the turbine housing has a bypass section and a twin scroll section formed by first and second scroll parts that are spaces defined in the turbine housing.
An example of conventional gravity casting molds for integrally casting the exhaust manifold and the turbine housing into a single body is referred to Korean Patent No. 1180951 (registered on Sep. 3, 2012, entitled “gravity pressure casting mold and gravity pressure casting method using the mold”).
The conventional gravity casting mold disclosed in Korean Patent No. 1180951 is problematic in that, although a riser for a turbine housing cavity is provided in the gravity casting mold, molten metal in the riser quickly cools, so molten metal may not be efficiently fed from the riser to the turbine housing cavity as the molten metal in the turbine housing cavity is cooling and shrinking, and this may cause shrinkage defects in a cast product that is a turbine housing.
The foregoing is intended merely to aid in the understanding of the background of the present invention, and is not intended to mean that the present invention falls within the purview of the related art that is already known to those skilled in the art.